What is concrete coring? Concrete coring is a core drilling technique that involves drilling cylindrical holes in concrete structures (floors, walls and ceilings) to accommodate new ducts, plumbing pipes, HVAC ducts, reinforcement and other systems. Core drilling is a reliable method for the extraction of representative samples from completed asphalt or concrete installations. Cores drilled from actual construction material provide the best samples for laboratory testing to assess material quality or verify compliance with project specifications. Most core drilling in today's construction projects is done to create access openings or to place utility conduits through a concrete structure.
In these cases, the core, the portion of material removed, is discarded as waste material. However, in the building materials testing sector, the goal is to recover the core. This blog post will focus on the method of core drilling and core sampling equipment. We will discuss why and how asphalt and concrete cores are sampled.
Finally, we address some of the different laboratory tests that are performed. The process of cutting asphalt or concrete cores is similar, but the reasons for sampling each of these materials are substantially different. By gravity, vibration or forced consolidation, Portland cement concrete consolidates into its final position while in a plastic state and remains there. It cures over time through the hydration process and hardens, developing high compressive strength.
ASTM C42 and AASHTO T 24 describe standard practices for the coring of hardened concrete elements and structures. ASTM C823 guides the planning of examination and sampling of concrete structures. There are a wide variety of types of drills available today, and some do a great job of drilling holes in concrete or asphalt materials. Our job is not to drill holes, but to extract high quality and uniform cores for laboratory testing.
This approach requires equipment with enough power and control to spin a drill bit straight through difficult materials. A drill motor mounted in a robust frame with a precision feed, solidly anchored to prevent vibration, displacement and seizure of the drill bit, directly affects the quality of the sample. Subtle differences in techniques and equipment produce optimal samples of asphalt or concrete materials. Asphalt pavement presents unique problems when coring.
It is softer than concrete, but also more abrasive. The frictional heat from the diamond drill bits makes the asphalt softer and more viscous. As the material softens, it can pinch the diamond drill bit, causing the drill to stop and damage the sample. Once the concrete has hardened sufficiently, it is easier to extract high quality, intact samples.
Coring during the early stages of curing, or when green, can damage the sample. It seems counter-intuitive, but concrete coring bits use a softer bonding material to set the diamonds. When cutting hard, brittle materials, diamonds fracture quickly and have a shorter life span. A softer bond matrix allows them to be washed away when they are no longer effective, exposing new diamonds to cut concrete more quickly.
We hope this blog post has helped you understand the core sampling methods and equipment to use for asphalt and concrete. Contact our testing experts to discuss your specific applications. Concrete core drilling involves drilling perfectly round holes in concrete walls, floors, ceilings and other structures. This fine-tunes the concrete structure to accommodate amenities such as telephone lines, plumbing, HVAC ducts, sprinkler systems and more.
A core drill is known as a non-percussive process. This means that the vibration caused by the drilling process is minimal. This causes minimal disturbance to the surrounding areas and minimises any related structural damage that could occur using other methods such as pneumatic hammers. Water is also applied to the cut surface to cool and suppress harmful concrete dust.
The advantages of core drilling are many and it is a very useful way of cutting concrete with many applications. If you ever need a true, deep or perfectly round hole in a concrete slab, it is your best choice. Commercially available units allow you to choose the right speed depending on the hardness of the concrete and the size of the hole. By drilling successive holes together, a process known as stitch drilling, thick concrete can be cut into any shape imaginable.
Concrete core drilling uses a diamond cutting bit to cut a perfect round hole in any concrete structure. Concrete core drilling is a fast, accurate and clean way to drill holes in concrete and is often listed as a basic service by most concrete cutting experts as Fine Cut. If you want a perfect round shaped hole in a horizontal or vertical concrete object, then core drilling is the way to go. In these cases, a lot of drilling has to be done in the concrete in order to install plumbing, electrical and computer conduits.
If you have to drill through the thickness of the concrete, the core will come out along with the drill bit. In concrete drilling, a diamond-tipped saw is used to make round holes of several different sizes to accommodate each type of access. The crank of the core drill itself drives the drill bit to the surface and cuts the concrete. One of the best uses of core drilling is to make core line holes in the thick concrete floor between levels and then connect the dots to remove a large portion of concrete.
Mastercut Concrete Cutting Sydney have been cutting concrete in Sydney for over 20 years and have a fleet of skilled and mobile concrete cutters equipped with a range of concrete core drills to suit your needs. Most concrete cutting companies offer this as a basic service and will have specialised diamond tipped core cutters that can easily undertake such jobs.